HOW TO SPOT AN ALTERED MANUFACTURE DATE ON A TYRE
There are some people in the market who know how to engrave a tyre. They engrave a "FAKE DATE" on the sidewall of the tyre. They achieve this by heating up a specially constructed iron rod (with numbers) and altering the MANUFACTURE YEAR on older tyres. For example, a tyre that has manufacture date 0312 (3rd week of 2012) could become 0316 (3rd week of 2016) after alteration. It is very difficult to spot this alteration (These guys are that "good").
HOW TO SPOT AN ALTERED MANUFACTURE DATE
Tyre dates are either embossed or debossed (stamped) by the manufacturer. When the date is embossed, you can use METHOD 1 to spot a fake date. However, when the date is debossed (stamped), you can spot a fake date by using METHOD 2.
METHOD 1: FOR EMBOSSED DATE
You can spot an altered manufacture date on a tyre by taking a closer look at the manufacture date. For example, if the manufacture date is "0316" (3rd week of 2016) and you notice that "031" is embossed, while "6" is debossed, just know that the manufacture date has been tampered with. These shady tyre dealers cannot create embossed "FAKE DATES" (at least for now). They can only create debossed dates by stamping. Though, some can go as far as erasing the date completely and writing a new one.
METHOD 2: FOR DEBOSSED DATE
Tyre dates are either embossed or debossed (stamped) by the manufacturer. When the date is embossed, you can use the above method to spot a fake one. However, when the date is debossed (stamped), you can spot a fake date by looking at the last digit in the date. For example if the debossed (stamped) date is "0316", you should take a closer look at "6" to check if it's as clear as the other digits "031". You should also check whether "6" is perfectly aligned (in a straight line) and of the same font size with the other digits "031".
Your best bet is to buy a popular brand from a trusted tyre dealer (preferably online). This is because most online tyre retailers get their tyres from authorised distributors who themselves get the tyres from the manufacturers, and not from parallel imports. You should also beware of online sites operated by shady tyre dealers.